A shot peening method for controlling the spherical deformation of the end head of a saddle-shaped wing skin

Abstract

The application discloses a shot peening shaping method for controlling the spherical deformation of a saddle-shaped wing skin end head, which uses a set of prestress tooling, and the prestress tooling comprises a support base, a support rod, an aluminum pad and a prestress wrench. The shaping method comprises marking a shaping area and a shaping direction, applying prestress, spreading pre-bending, detecting the spreading pre-bending amount, ultrasonic shot peening shaping and detecting the skin shape. The application applies prestress to the wing skin end head through a set of prestress tooling, so that the skin end head generates spreading pre-deformation, the amount of deformation is detected by using a spreading template, the skin end head is subjected to ultrasonic shot peening shaping in a prestress state, the skin end head shape is detected by using a chordwise and spreading template, and it is ensured that the skin shape meets the design requirements.

Description

Technical Field

[0001] This invention relates to the field of aircraft wing skin shaping technology, and is an ultrasonic shot peening method for correcting the spherical deformation of the wing skin ends caused by shot peening forming when the wing skin has a saddle shape. Background Technology

[0002] Currently, the wing skins of large and medium-sized aircraft are all of double curvature shape, meaning they possess both chordal and spanwise curvature. After the wing skin is integrally shot-peened on a CNC shot-peening machine, it cannot be precisely formed in one step and requires local shot-peening correction to meet the final double curvature shape requirements. For double curvature wing skins with a "saddle" shape, where the chordal and spanwise curvatures bend in opposite directions, the lack of constraint at the skin ends after shot-peening will produce a significant "spherical deformation" effect, meaning the chordal and spanwise curvatures bend in the same direction. In this case, shot-peening correction is necessary to eliminate the "spherical deformation" tendency.

[0003] Common shot peening and shaping methods are divided into CNC shot peening machine shaping and manual ultrasonic shot peening shaping. The former is suitable for shaping larger areas and is carried out under prestress, while the latter is suitable for shaping smaller areas, especially areas where prestress cannot be applied on the machine tool, such as the ends of wing skin.

[0004] For the spherical deformation of the wing skin tip, since the deformation area is close to the tip and only 100mm-200mm wide, effective pre-bending and shot peening correction cannot be performed on a CNC shot peening machine. Therefore, ultrasonic shot peening is currently used for manual shot peening correction. However, during ultrasonic shot peening correction, the deformation direction is difficult to control, and reverse spherical deformation is very likely to occur, resulting in insufficient chordal shape. At this time, it is necessary to perform chordal correction on the skin tip to increase the chordal deformation. Repeated correction to gradually approach the target shape will cause excessive material elongation, resulting in wing skin shape instability and out-of-tolerance geometric dimensions, causing irreversible consequences and making it difficult to meet the design requirements for wing skin shape and surface quality.

[0005] Therefore, there is an urgent need for an ultrasonic shot peening method suitable for saddle-shaped wing skin to solve the current shot peening problem of spherical deformation in the end area of ​​wing skin, ensure coordinated deformation of the skin chord span during the shaping process, reduce shaping risks, and improve product quality. Summary of the Invention

[0006] To address the aforementioned problem of spherical deformation at the tip of wing skin, this invention provides a shot peening and straightening method for controlling the spherical deformation at the tip of a saddle-shaped wing skin. A prestressing fixture is used to apply prestress to the tip of the wing skin, causing spanwise pre-deformation. A spanwise template is used to detect the deformation. Ultrasonic shot peening is then performed on the tip of the skin under prestress. Both chord and spanwise templates are used to inspect the shape of the tip of the skin, ensuring that the skin shape meets design requirements.

[0007] A shot peening method for controlling the spherical deformation of the saddle-shaped wing skin tip includes a prestressing fixture. The fixture comprises a support base, a support rod, an aluminum pad, and a prestressing wrench. The support rod is mounted on the support base through a fixing hole and connected to the aluminum pad via a slot. The support base is a rigid base, with a threaded rigid support rod installed in the central fixing hole, allowing adjustment of the support rod's height via the thread. The top of the support rod has a slot for mates with the aluminum pad, which is mounted on the top of the support rod via the slot. The top of the aluminum pad, where it contacts the skin, is arc-shaped, and the bottom has a slot for connecting to the support rod. The prestressing wrench has a slot in the middle of its thickness surface at one end, the slot width being 2mm larger than the skin thickness, and a polyurethane elastic pad is installed at the contact point between the slot sidewall and the skin.

[0008] The calibration method includes the following steps:

[0009] Step 1: Mark the correction area and correction direction

[0010] A correction area is marked on the inner surface of the wing skin tip. The correction area starts 50 mm from the skin tip and extends 150 mm spanwise, meaning the width of the correction area in the spanwise direction is 100 mm. Correction paths are marked within the correction area, with the direction of the correction paths being the same as the spanwise curvature direction, and the spacing between each correction path in the chord direction is 100 mm.

[0011] Step 2: Apply prestress

[0012] A tangential template is installed on the outer surface of the skin, 600 mm from the skin end. The area within 400-600 mm of the inner surface of the skin is the prestressing zone, with a prestressing rate of 7.6 kg / 0.04 m. 2 The loading requirement is to place sandbags in the prestressing application area to apply prestress.

[0013] Step 3: Spreading pre-bending

[0014] Insert the top of the adjustable support rod into the slot of the aluminum pad and place it under the skin. The aluminum pad is 200mm long. Adjust the height of the support rod so that the aluminum pad contacts the outer surface of the skin. Adjust the direction of the aluminum pad so that its length direction is perpendicular to the spanwise curvature direction of the skin. Adjust the position of the support rod along the spanwise curvature direction of the skin so that the aluminum pad is in the middle of the correction area. Using a prestressing wrench, insert the end of the skin into the prestressing wrench slot with a depth of 20mm. Bend the end of the skin towards the outer surface of the skin using the prestressing wrench to apply prestress to the end of the skin, causing the end to undergo spanwise pre-deformation.

[0015] Step 4: Detect spanwise pre-bending.

[0016] The spanwise deformation is detected using a spanwise template on the inner surface of the skin. The gap between the skin and the spanwise template is controlled within 0.5 mm to ensure that the spanwise deformation at the skin end meets the process requirements and is within the elastic deformation range.

[0017] Step 5: Ultrasonic shot peening and shaping

[0018] Using an ultrasonic shot peening machine, the wing skin end shaping area and path marked in step 1 were ultrasonically shot peened for shaping. During shaping, the ultrasonic shot peening machine struck the part along the spanwise curvature direction, and steps 3 and 4 were repeated every 100mm along the chordal direction. This ensured that all shaping areas were shaped under prestress, achieving spanwise deformation of the wing skin end without affecting the chordal shape.

[0019] Step 6: Inspect the shape of the skin.

[0020] Use a spanwise template to inspect the spanwise shape of the wing skin tip on the outer surface of the skin, and use a chordwise template to inspect the chordwise shape of the wing skin tip on the outer surface of the skin, to ensure that the gap between the skin and the spanwise and chordwise templates meets the design requirements.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) It solved the problem of spherical deformation at the end of the saddle-shaped wing skin, and filled the gap in the method of small-range pre-bending at the end of the skin (100mm-200mm).

[0023] (2) It solves the problem of difficulty in controlling the deformation direction caused by manual correction, and improves the accuracy of correction;

[0024] (3) It avoids the risks of excessive skin stretching and uncontrollable geometric shape caused by repeated reshaping;

[0025] (4) It reduced the number of calibrations and improved calibration efficiency. Attached Figure Description

[0026] Figure 1 Schematic diagram of ultrasonic shot peening and straightening fixture structure

[0027] Figure 2 Schematic diagram of prestressing application at the wing skin tip

[0028] Figure 3 Schematic diagram of wing skin tip spanwise shape inspection

[0029] Numbering in the diagram: 1. Prestressing wrench; 2. Support base; 3. Support rod; 4. Aluminum pad; 5. Prestressing application area; 6. Shaping area; 7. Inner surface of skin; 8. Outer surface of skin; 9. Tangential template; 10. Transverse template; 11. Straight ruler Detailed Implementation

[0030] The following example, using ultrasonic shot peening to correct the spanwise prestress of a double-curvature skin end of an aircraft using a special prestressing tool, illustrates the specific implementation of this invention:

[0031] like Figure 1 As shown in Figure 3, a shot peening method for controlling the spherical deformation of the saddle-shaped wing skin tip includes a prestressing fixture. The prestressing fixture includes a support base 2, a support rod 3, an aluminum pad 4, and a prestressing wrench 1. The support rod 3 is mounted on the support base 2 through a fixing hole and connected to the aluminum pad 4 through a slot. The support base 2 is a rigid base, with a threaded rigid support rod 3 installed in the fixing hole in the middle. The height of the support rod 3 can be adjusted via the thread. The top of the support rod 3 has a slot for mates with the aluminum pad 4, which is mounted on the top of the support rod 3 through the slot. The top of the aluminum pad 4 that contacts the skin is arc-shaped, and the bottom has a slot for connecting to the support rod 3. The prestressing wrench 1 has a slot in the middle of its thickness surface at one end. The slot width is 2mm larger than the skin thickness, and a polyurethane elastic pad is installed at the position where the slot sidewall contacts the skin.

[0032] 1. Mark the correction area and correction direction.

[0033] Using a 200mm long straightedge 11, place it against the inner surface 7 of the skin along the spanwise direction, aligning one end of the straightedge 11 with the end of the skin. Mark the area within 200mm of the skin end where the maximum indentation occurs, i.e., the 60mm area with the greatest deflection. Mark a correction area on the inner surface of the skin end, starting 50mm from the skin end and extending 150mm along the spanwise direction, i.e., the width of the correction area along the spanwise direction is 100mm. Mark correction paths within the correction area, with the direction of the correction paths being the same as the spanwise curvature direction, and the spacing between each correction path along the chordwise direction is 100mm.

[0034] 2. Apply prestress

[0035] A tangential template 9 is installed on the outer surface 8 of the skin, 600 mm from the end of the skin. The area 5 for applying prestress to the skin, ranging from 400 to 600 mm from the end of the skin, is located on the inner surface 7 of the skin, with a prestressing rate of 7.6 kg / 0.04 m. 2 The loading requirement is to place sandbags in the prestressing application area 5 to apply prestress.

[0036] 3. Transverse pre-bending

[0037] Insert the top of the adjustable support rod 2 into the dovetail groove of the aluminum pad 4 and place it below the outer surface 8 of the skin. The length of the aluminum pad 4 is 200mm. Adjust the height of the support rod 2 so that the aluminum pad 4 contacts the outer surface 8 of the skin. Adjust the direction of the aluminum pad 4 so that its length direction is perpendicular to the spanwise curvature direction of the skin. Adjust the position of the support rod 2 along the spanwise curvature direction of the skin so that the aluminum pad 4 is located in the middle of the straightening area 6. Use the prestress wrench 1 to insert the end of the skin into the groove of the prestress wrench 1 with a groove depth of 20mm. Bend the end of the skin towards the outer surface 8 of the skin using the prestress wrench 1 to apply prestress to the end of the skin, so that the end produces spanwise pre-deformation.

[0038] 4. Detect the spanwise pre-bending amount

[0039] The spanwise deformation is detected on the outer surface 8 of the skin using a spanwise template 10. The gap between the skin and the spanwise template 10 is controlled within 0.5 mm to ensure that the spanwise deformation at the skin end is within the elastic range.

[0040] 5. Ultrasonic shot peening and straightening

[0041] Using an ultrasonic shot peening machine, the wing skin end shaping area 6 and the shaping path marked in step 1 were ultrasonically shot peened for shaping. During shaping, the ultrasonic shot peening machine struck the part along the spanwise curvature direction, and steps 3 and 4 were repeated every 100mm along the chordal direction. This ensured that all shaping areas were shaped under prestress, achieving spanwise deformation of the wing skin end without affecting the chordal shape.

[0042] 6. Inspect the shape of the skin.

[0043] The spanwise template 10 is used to inspect the spanwise shape of the wing skin tip on the outer surface 8 of the skin, and the chordwise template 9 is used to inspect the chordwise shape of the wing skin tip on the outer surface 8 of the skin. This ensures that the fit gap between the skin and both the spanwise template 10 and the chordwise template 9 is within 0.5mm, meaning that the skin shape meets the design requirements.

Claims

1. A shot peening method for controlling the spherical deformation of the skin tip of a saddle-shaped wing, characterized in that... The system includes a prestressing fixture comprising a support base, a support rod, an aluminum pad, and a prestressing wrench. The support rod is mounted on the support base through a fixing hole and connected to the aluminum pad through a slot. The support base is a rigid base, with a threaded rigid support rod installed in the fixing hole in the middle. The height of the support rod can be adjusted via the thread. The top of the support rod has a slot for mates with the aluminum pad, which is mounted on the top of the support rod through the slot. The top of the aluminum pad that contacts the skin is arc-shaped, and the bottom has a slot for connecting to the support rod. The prestressing wrench has a slot in the middle of its thickness surface at one end, with the slot width 2mm greater than the skin thickness. A polyurethane elastic pad is installed at the position where the slot sidewall contacts the skin. The calibration method includes the following steps: Step 1: Mark the correction area and correction direction. The specific process is as follows: Mark the correction area and correction direction. Mark the correction area on the inner surface of the wing skin tip. The correction area starts from 50mm away from the skin tip and extends along the spanwise direction to 150mm. That is, the width of the correction area along the spanwise direction is 100mm. Mark the correction path within the correction area. The direction of the correction path is the same as the spanwise curvature direction, and the spacing of each correction path along the chordwise direction is 100mm. Step 2: Apply prestress. The specific process is as follows: Set a tangential template on the outer surface of the skin, 600mm from the skin end. The prestressing area on the inner surface of the skin, 400-600mm from the skin end, is the prestressing zone. Apply prestress at a rate of 7.6kg / 0.04m. 2 The loading requirement is to place sandbags in the prestressing application area to apply prestress; Step 3: Spreading pre-bending; Step 4: Detect spanwise pre-bending. Step 5: Ultrasonic shot peening for shaping; Step 6: Inspect the shape of the skin.

2. The shot peening method for controlling the spherical deformation of the skin tip of a saddle-shaped wing according to claim 1, characterized in that... Step 3, spanwise pre-bending, specifically involves inserting the top of the adjustable support rod into the slot of the aluminum pad and placing it below the skin. The height of the support rod is then adjusted so that the aluminum pad contacts the outer surface of the skin. Adjust the direction of the aluminum pad so that its length direction is perpendicular to the spanwise curvature direction of the skin; adjust the position of the support rod along the spanwise curvature direction of the skin so that the aluminum pad is located in the middle of the correction area; use a prestressing wrench to insert the skin end into the prestressing wrench slot, and bend it towards the outer surface of the skin to apply prestress to the skin end, so that the end produces spanwise pre-deformation.

3. The shot peening method for controlling the spherical deformation of the skin tip of a saddle-shaped wing according to claim 1, characterized in that... Step 4, detecting the spanwise pre-bending amount, specifically involves using a spanwise template on the inner surface of the skin to detect the spanwise deformation. The gap between the skin and the spanwise template is controlled within 0.5mm to ensure that the spanwise deformation at the skin end meets the process requirements and is within the elastic deformation range.

4. The shot peening method for controlling the spherical deformation of the skin tip of a saddle-shaped wing according to claim 1, characterized in that... Step 5, ultrasonic shot peening and straightening, specifically involves using an ultrasonic shot peening machine to perform ultrasonic shot peening and straightening on the wing skin end straightening area and straightening path marked in step 1. During straightening, the ultrasonic shot peening machine strikes the part along the spanwise curvature direction, and repeats steps 3 and 4 every 100mm along the chord direction to ensure that all straightening areas are straightened under prestress, achieving spanwise deformation of the wing skin end without affecting the chordal shape.

5. The shot peening method for controlling the spherical deformation of the skin tip of a saddle-shaped wing according to claim 1, characterized in that... Step 6, inspecting the skin shape, specifically involves: using a spanwise template to inspect the spanwise shape of the wing skin end on the outer surface of the skin, and using a chordwise template to inspect the chordwise shape of the wing skin end on the outer surface of the skin, ensuring that the gap between the skin and the spanwise and chordwise templates meets the design requirements.

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